高压物理学报

The Polarizability of Material under Shock Loading

ZHANG Guan-Ren

1990, 4(3): 161-166 . doi: 10.11858/gywlxb.1990.03.001

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Abstract:
The polarization and depolarization processes in material under shock loading are interpreted by the theory of dislocation. The formula for calculating the polarizability under shock loading is derived in this paper. The conclusion is that the ppolarizability not depends upon the dislocation density but also upon the spectrum of the shock wave.

Theoretical Study of the Spectrum of Ruby

SHEN Yi-Min, LI Bo-Fu, SUN Jia-Zhong

1990, 4(3): 167-174 . doi: 10.11858/gywlxb.1990.03.002

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Abstract:
A restricted Hartree-Fock SCF calculation on ruby was carried out. The excitation energies of d-d transition in ruby was calculated by means of irreducible tensor method based on the calculated molecular orbitals. The calculated excitation energies agree fairly well with those observed within 900 cm-1. In addition, calculation results show that the frequency of the ruby R1 line (4A12E) decreases as pressure increases.

A Simplified Analytical Method for Calculations of Equation-of State of Materials from Shock Compression Data

HU Jin-Biao, JING Fu-Qian

1990, 4(3): 175-186 . doi: 10.11858/gywlxb.1990.03.003

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Abstract:
Assuming (1) the Born-Meyer potential, (2) with negligible electron contribution to thermal energy, and (3) with a linear relation between the shock and particle velocities are valid for materials to be studied, an analytical approach is proposed in this paper for calculating the binding energy and the corresponding Grneisen equation-of-state of those materials. Seventeen metals, including Be, Al, Cu, Ta, U etc, are used as example to test the applicability of the proposed method by calculating the values of Q, q which are two parameters in Born-Meyer potential. In comparison with those give from Refs [13-14], it is found that there appears a satisfactory agreement among the data from these three different sources with a few exceptions of Be, Ni and Pb, and the validity of this method is also proved. The possible causes of the discrepancies in Be, Ni and Pb are also discussed in paper.

Scaling Theory and Fractal Geometry

DONG Lian-Ke, Lü Guo-Hao, WANG Ke-Gang, WANG Xiao-Wei

1990, 4(3): 187-193 . doi: 10.11858/gywlxb.1990.03.004

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Abstract:
In this paper, the relation of perimeter-are and the length formula of ordinary fractal curve in fractal are considered by the method of the dimensional analysis; the quantitative relation between the ordinary scaling transformation and scaling transformation in fractal is established. Finally, we give F-P equation of fractional Brownian moton.

The Electronic Structure of High Temperature Superconducting Material YBa2Cu3O7 under High Pressure

WANG Huai-Yu, ZHANG Li-Yuan, LIU Fu-Sui, WANG En-Ge

1990, 4(3): 194-203 . doi: 10.11858/gywlxb.1990.03.005

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Abstract:
The electronic structure of YBa2Cu3O7 under atmosphere and 9 GPa high pressure (under which the crystal constants are contracted by 3%) are calculated, respectively. In calculation, recursion method is used and the tight binding Hamiltonian is constructed by Harrison parameters fitted to energy band. The influence of high pressure on electronic structure is discussed. The quantitative results about shift of Fermi surface, widening of energy band width and varying of atomic valence of each crystal site are given.

The Temperature Control for the Growth of Synthetic Diamond

QI Zeng-Du

1990, 4(3): 204-209 . doi: 10.11858/gywlxb.1990.03.006

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Abstract:
This paper discusses the temperature control for the growth of synthetic diamond, associated with the cell assembly, temperature gradient in the cell and boundary condition.

Experimental Studies on the Dynamic Behaviour of Polytetrafluoroethylene (PTFE)

LI Xiao-Lan, WANG Zhan-Jiang

1990, 4(3): 210-217 . doi: 10.11858/gywlxb.1990.03.007

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Abstract:
The shock adiabat of PTFE (with the initial density 2.19 g/cm3) has been measured with the impedance matching method at high pressures. LY-12 Al was used as a standard material (the initial density is 2.794 g/cm3, and the linear relation between the shock velocity D and the particle velocity u is D=5.47+1.28u (mm/s).). In the experiments, the plane shock waves were produced by means of the contact explosion technique or the flyer impact technique, and the shock velocity D was measured by the high-speed scanning photography combined with the flash-gap technique. Is the pressure range from 10 to 55 GPa, the obtained linear relation between D and u of PTFE is D=2.10+1.62u (mm/s). At lower pressures (0.2~3 GPa), the experiments were conducted on a gas-gun with the symmetric impact principle, the impact velocities were measured by a laser system the Lagrange particle velocity profiles for loading and unloading processes and the shock velocity in the specimen were measured with the electro-magnetic velocity gages. For the shock loading process, the obtained D-u relation and the shock adiabat are respectively. D=1.24+3.72u-1.94u2 (mm/s) and =2.10+44.52+123.23 where is the axial stress behind the shock front for one-dimensional strain, and is the corresponding bulk strain. The obtained unloading paths are almost in agreement with the shock adiabat. The residual strains seem to be either inexistent or very small. The elastic behavior almost does not occur; i. e. PTFE presents plastic behavior essentially.

Large cBN Crystal Synthesis

ZHANG Tie-Chen, ZOU Guang-Tian, GUO Wei-Li, XU Xiao-Wei, MA Wen-Hun, GUO Xue-Bin

1990, 4(3): 218-222 . doi: 10.11858/gywlxb.1990.03.008

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Abstract:
Single crystals of cubic boron nitride with a diameter of about millimeter order were obtained by controlling the nucleation rate of cBN crystal under 4.5~6.0 GPa and 1 500~1 900 ℃ for several minutes. The maximal size of the cBN single crystals is 1.6 millimeter. The growth characteristic and mechanism of cBN crystal were also discussed.

600 kJ Power Supply System and Its Application in Railgun

GAO Shun-Shou, LENG Guan-Song, HAN Jun-Yu, LONG Xin-Ping, WU Shou-Dong, FENG Shu-Ping, CHEN Su-Nian

1990, 4(3): 223-228 . doi: 10.11858/gywlxb.1990.03.009

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Abstract:
A 600 kJ power supply system for the railgun system is presented. A capacitor bank is used as its primary power. Effective energy transfers from the primary power to a railgun through a transform circuit with inductor and crowbar. Explosively driven, metal-to-metal contact, solid dielectric switches have been developed as master switch and crowbar. An empirical medal to describe the switch resistance time-dependence has been proposed. Experimental results show that the system operates well.

A New Theory of MeltingA Model of Quantum Motion of Dislocation

LIN Hua-Ling, SUN Feng-Guo

1990, 4(3): 229-233 . doi: 10.11858/gywlxb.1990.03.010

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Abstract:
A new theory of melting has been proposed. Start from a model of quantum motion of dislocation in P-N potential, we obtained the melting point of crystals, the results are in agreement with the experimental values.

Estimation of the Thermal Shock Wave and Spall of Aluminum Alloy Irradiated by an Electron Beam

ZHOU Yi-Chun, PENG Chang-Xian

1990, 4(3): 234-240 . doi: 10.11858/gywlxb.1990.03.011

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Abstract:
In this paper, we estimate the thermal shock wave and spall effect of LY-12 aluminum exposed to a high-current and low-energy relativistic electron beam. Melting process must be adequately taken into accounted for the material dynamic response calculation in the intermediate energy deposition range. The equation-of-state (EOS) used is GRAY three-phase EOS, which gives a more detailed and complete thermodynamical description of metals in the melting range. The calculated results are basically consistent with the experimental results.

1990 Vol. 4, No. 3

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